1. Field of the Invention
This invention relates to solid and semi-solid state polymer electrolyte composites which contain an inert electrically insulating woven or non-woven glass fiber net, which is coated with an ion conductive solid or semi-solid state matrix.
2. Description of the Prior Art
In the prior art various polymers have been used as components of the electrolytes of solid state alkali metal, and alkaline earth metal batteries, and various other kinds of electrochemical devices.
Among the problems associated with the use of these polymers in electrolytes is that they have inherent relatively low ionic conductivity, and are not tough enough to prevent shorting during assembly or use.
Various solutions have been proposed such as described in the U.S. Patents to Hope et al., U.S. Pat. Nos. 5,102,752; 5,328,558; Schwabet et al., U.S. Pat. No. 4,792,504; Ballard et al., U.S. Pat. No. 4,822,701; Bauer et al., U.S. Pat. No. 4,654,279; Lee et al., U.S. Pat. No. 4,830,939; Lee et al., U.S. Pat. No. 4,990,413, and Kejha U.S. Pat. No. 5,521,023.
Some of the prior art polymer containing electrolytes also have exhibited poor adherence to the electrodes, are not flexible and do not possess sufficient mechanical strength to prevent shorting under pressure, or punching through of dendrites and consequent shorting of the device.
While electrically insulating fibrous structures in solid ribbon or mesh form are used in composite electrolytes, and are satisfactory for their intended purpose, the fibrous non-woven fabrics are thick, heavy, bulky, may absorb moisture, and may also cost more than is optimal. None of the prior art patents suggests, discloses or describes the composite electrolytes described herein.
The composite polymer electrolytes of the invention do not suffer from the prior art problems and provide many positive advantages.